Insights on the activity of the anaerobic digestion microbiome by means of metatranscriptomic functional investigation

produce high-value pure influence of operational parameters (e.g. temperature, pH, feedstock composition, etc.) on microbial activity needs to be addressed. A set of metatranscriptomic studies have been performed in replicate biogas reactors with the aim of correlating the microbial community structure and their changes in gene expression with the variations in process parameters. The first study investigated the transcriptional changes in a community after radical shifts of the influent feedstock determined by the addition of long chain fatty acids (LCFA). The importance of Syntrophomonas species was confirmed and the activation of chemotaxis genes was evidenced in several species; moreover an increased gene expression in Methanosarcina sp. was recorded (Treu et al. , 2016). Other two ongoing studies are focused on hydrogenotrophic methanogenesis and the role of syntrophic bacteria in the biogas production improvement obtained by the conversion of CO 2 into CH 4 via external hydrogen addition. Moreover, acetate accumulation and pH fluctuations were analyzed to identify the microbial key functions and correlate them with